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## electromagntic propagation through three layers

Posted 18/01/2013, 05:54 GMT-05:00 RF & Microwave Engineering Version 4.1 15 Replies

I am student on electronic and I am trying to simulate with comsol on rf module , in summarize my work is to simulate the sun light propagation through three layers bonded to each other and I had used the floquet periodic condition and this witch include this equations :

Parameter

lambda0= 0.5e-6[m]

k0_emwh = 2*pi/lambda0

alpha1 =30[deg]

n1 1.97235

k1x= k0_emwh*real(n1)*cos(alpha1)

k1y =k0_emwh*real(n1)*sin(alpha1)

freq c/lambda0

c= 3*10^8[m/s]

n2 0.125

alpha2= asin(sin(alpha1)*real(n1/n2))

k2x= k0_emwh*real(n2)*cos(alpha2)

K2y= k0_emwh*real(n2)*sin(alpha2)

n3 1.97235

alpha3 =asin(sin(alpha3)*n2/real(n3))

E0z= exp(-i*k1x*x)

Ez1= E0z[V/m]

k3x= k0_emwh*real(n3)*cos(alpha3)

k3y= k0_emwh*real(n3)*sin(alpha3)

and I put the boundary condition above and below the layers

Periodic condition 1

K vector for folquet periodicity :

k1x

k1y

Port 1

In the front of the layer

Put the wave excitation in this port (on)

Pin=1

Téta(in) = 0

E0= Ez1

Beta =k1y

Port 2

Put the wave excitation in this port (off)

E0= Ez1

Beta =k1y

in this simulation i would like to study the propagation of the electromagnetic wave through three micrometer thickness of material, and each material have property , and my problem when reduce the thickness the electromagnetic wave propagate with difficulty and when i increase the thickness the wave propagate easily, i don't know if my simulation is true.

Thank you for your help

Attachments:

Several notes about your model:

1) Expressions such as E0z= exp(-i*k1x*x) should be defined under Model>Definitions>Variables but not under Global Definitions>Parameters as in your model, since E0x depends on spatial coordinates. That is why your parameter is highlighted as red.

2) Propagation constant in the port conditions should be normal component of the wavector, not parallel. That is, beta=k1x and not beta=k1y as in your model.

3) I assume you want to analyze TE polarization. In that case, incident wave should be defined as E={0,0, exp(-i*k1y*y) }, not E={0,0,exp(-i*k1x*x)} as in your model.

4) Consider creating mesh with several elements through the thickness of the thin middle layer using Mapped mesh.

5) If you are not sure about your results, compare Comsol results with analytical solution for multilayer structures available in textbooks. Numerical and analytical solutions should be in perfect agreement for all incidence angles for 0 to 90 degrees.

Regards,

Sergei

I'll try i'll try to change what are you had tell , just I would like tell you i use the floquet periodic condition, i suppose it's the same , i ll give you the results that i found

I redid my simulation with your modification but it's the same results , and in this simulation i want to study the electromagnetic wave propagation through x axes , can you help me please .

thank you

I don’t have 4.1, so I am attaching report of your model created with later version. Comparison with analytical solution for the case of TM polarization is also included.

I set the conductivity of the first ZnO layer to zero because it does not make much sense to specify evanescent wave at the input port. If you want to study wave attenuation in the first ZnO layer, then you might want to model structure with four layers: first layer is lossless dielectric (say, air) where you specify incident wave, second layer is ZnO with specified thickness, etc.

Regards,

Sergei

Attachments:

Attached is model file. Please note that this is 4.3a.

Regards,

Sergei

Attachments:

I don't have 4.3 A version , but I am trying to work under 4.1 version with you last exemple , when I finish I post the result

I have a small problem with parameter equation when i try to enter this equation in parameter case

sqrt(k0^2*em - kay^2 - j*eps^3)

x-component of wavevector of middle layer (evanescent square root)

the comsol don't accept this , and I would like to know what the

eps

thank you

eps is small number. Under Global Parameters, define a=eps and you will see that it's numerical value is 2.22e-16.

If you define eps1=1e-12, it will be OK.

Sergei

indeed "eps" is a predefined number in COMSOL (as in other numerical tools) it's the smalles real number one can distinguish from "1.0" in the binary representation of real numbers. It's rather FPU dependent, so you can forget to put it to any positive power it will wanish.

Even, as most physics equations are 2nd order PDE's then sqrt(eps) represents, the absolute best, relative ratio, or number of significant digits you could expect from your results

--

Good luck

Ivar

this is what I've done but it's still wrong , but the notation in certain parameter indicate with red color , please if some one can correct me ,i am always trying to find a solution , in parallel if i find something i poste

thank you

red means normally typos, or undefined variable name:s so those should be tracked and corrected,

orange is unit inconsistencies, thise might be ignored, with the risk of scaling errors

--

Good luck

Ivar

just I finished my simulation through the last exemple , but in last part from the example i don't understand how to obtain the diagram refraction in 1 D plot groupe can help you me to have the diagrme

thank you

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